Brain surgery commonly involves the removal or destruction of suspect regions. For example, for brain tumors surgical resection is often the first treatment of choice. For drug resistant epilepsy, removal or destruction of the epileptic focus by surgical means is an important treatment. Brain surgery does not always involve open surgery, but is nowadays also performed in non-invasive ways of utilizing, e.g., stereotactic radiosurgery. During brain surgery, it is very important not to damage critical structures and connections in the brain. Damaging brain tissue during an operation usually leads to function loss afterwards. The brain has some ability to recover when damaged, but this ability is limited. Minimizing damage made during surgical intervention or radiotherapy is achieved by carefully planning the surgery using pre-operative medical images like MRI.
Often intra-operative visualization (microscope, ultrasound, MR, X-ray) is used to provide imaging information during the procedure. Diffusion-tensor MRI (DTI) based tractography can be considered as a very advanced anatomic imaging modality that visualizes the important white-matter tracts in the brain that connect different brain regions. The registration of all these data to a common framework and the combined visualization of these data provide surgeons with a detailed anatomical map of the brain that supports them in determining an optimal surgical plan.
Today, most advanced brain-surgery planning systems take into account both anatomical image information (contrast-enhanced MRI, CT, etc., that high-light specific brain anatomy) as well as functional image information (fMRI, PET, MEG, EEG, etc., that high-light specific brain function). Functional brain imaging is aimed at characterizing the brain in terms of its physiology, functional architecture and dynamics. Functional imaging can be based on analysis of data acquired using brain imaging modalities such as electro-encephalography (EEG), magneto-encephalography (MEG), functional magnetic resonance imaging (fMRI), or optical techniques such as near-infrared spectroscopy (NIRS).
A neurosurgical planning system visualizing both functional and anatomical data is known from the US patent application published as US 2005/0273001 A1. The system described in that application uses fMRI images, DTI images and perfusion images of the brain and selectively displays them on top of one another. All displayed images are aligned with an anatomical image of the brain. The transparency of each layer can be adjusted. Although such a system has some advantages over systems using only anatomical imaging, there is a need for a smarter and more sophisticated combination of anatomical and functional data in order to allow the surgeon to make a better informed decision and to increase the ability to minimize function loss after the operation.
It is an object of the invention to provide a system and method for planning a neurosurgical operation, which system and method improve the ability to avoid function loss after the operation.